1. Field of the Invention
The present invention generally relates to fluid handling machines and, more particularly, is concerned with a non-contact vane-type fluid displacement machine having features of improved designs and constructions.
2. Description of the Prior Art
U.S. Pat. Nos. 5,087,183 and 5,160,252 to Thomas C. Edwards, also the inventor herein, disclose a non-contact vane rotary fluid displacement machine of unique design and superior performance in terms of reliability, economy and low noise characteristics. The machine can provide fluid displacement functions for numerous different consumer and industrial products. One important fluid displacement function of the machine is as a compressor. The provision of effective compression of gases in a compressor is a challenging technical and economic task. Commercially viable positive displacement compressors embody means for efficiently confining gases within dynamic sealing chambers formed by extremely close-fitting mechanical parts. For example, in conventional rotary-vane, screw, and scroll compressors, the side clearance between rotor faces and endplates are limited to about 0.0005 inch. For that reason, only a few types of compressors have reached commercial prominence. These compressors, to one degree or another, reach sufficient energy efficiency by achieving very small dynamic interface sealing clearances.
Not only are these tiny dynamic clearances difficult to achieve during manufacture, but as the pressure develops within the compressors when they are operating, the internal loads created by these operating pressures tends to increase these very small leakage gaps. Therefore, it is critical to design the compressors to not only achieve very close "cold" or non-operating clearances at manufacture, but to ensure that they do not increase significantly during operation. The latter can be achieved only through providing extremely rigid structural embodiments.
A characteristic of most compressor engineering and design is that it is not generally possible to achieve ideal design configurations that simultaneously present the highest efficiency and reliability at the lowest cost. Almost always, lower cost results in both lower energy efficiency and lower reliability. Thus, the innovator is faced with creating concepts and configurations that deal with economic constraints through knowledge of the relative importance of cost, reliability, and energy efficiency in a given compressor application.
A major application for a compressor is the automotive air conditioning compressor market. Due to its size and highly competitive nature, this market prefers compressors that are high energy efficiency, low in cost and have robustness. However, reliability is the predominant design requirement. Thus, high machine reliability predominates over energy efficiency from the standpoint of cost limitations.
The non-contact vane rotary fluid-handling machine of the above-cited Edwards patents has shown great promise as a compressor. However, further improvements in design and construction are desired to enhance the performance of this machine as a compressor, such as in the highly competitive automotive air conditioning compressor market.